Escaping JavaScript Strings in Python

Question

I have a Python script that builds some JavaScript to send down to the browser in a JSON envelope. I'd like to escape the JavaScript strings and delimit them with single quotes. I can't use json.dumps because it uses double quotes as delimiters like the JSON spec requires.

Is there a JavaScript String escape method in Python?

Example

def logIt(self, str):
    #todo: need to escape str here
    cmd = "console.log('%(text)s');" % { 'text': str}
    json.dumps({ "script": cmd })

So logIt('example text') should return something like this:

{
  "script": "console.log('example text');"
}

Answer 1

json.dumps is that escaping function - it takes any value, and makes it a valid javascript literal.

def logIt(self, str):
    cmd = "console.log({0});".format(json.dumps(str))
    json.dumps({ "script": cmd })

Producing:

>>> print logIt('example text')
{ "script": "console.log(\"example text\");" }
>>> print logIt('example "quoted" text')
{ "script": "console.log(\"example \\\"quoted\\\" text\");" }

---

Or:

import string
import json
import functools

quote_swap = functools.partial(
    string.translate, table=string.maketrans('\'"', '"\'')
)

def encode_single_quoted_js_string(s):
    return quote_swap(json.dumps(quote_swap(s)))